[sensors] Add GetDefaultConfiguration() to generic sensor mojo interface.

device/generic_sensor/sensor_impl.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef DEVICE_GENERIC_SENSOR_SENSOR_IMPL_H_
 #define DEVICE_GENERIC_SENSOR_SENSOR_IMPL_H_
 
 #include "base/macros.h"
 #include "device/generic_sensor/platform_sensor.h"
 #include "device/generic_sensor/public/interfaces/sensor.mojom.h"
 #include "mojo/public/cpp/bindings/strong_binding.h"
 
 namespace device {
 
 // Implementation of Sensor mojo interface.
 // Instances of this class are created by SensorProviderImpl.
 class SensorImpl final : public mojom::Sensor, public PlatformSensor::Client {
  public:
   SensorImpl(mojo::InterfaceRequest<mojom::Sensor> request,
              scoped_refptr<PlatformSensor> sensor);
   ~SensorImpl() override;
 
   mojom::SensorClientRequest GetClient();
 
  private:
   // Sensor implementation.
   void AddConfiguration(const PlatformSensorConfiguration& configuration,
                         const AddConfigurationCallback& callback) override;
+  void GetDefaultConfiguration(
+      const GetDefaultConfigurationCallback& callback) override;
   void RemoveConfiguration(
       const PlatformSensorConfiguration& configuration,
       const RemoveConfigurationCallback& callback) override;
   void Suspend() override;
   void Resume() override;
 
   // device::Sensor::Client implementation.
   void OnSensorReadingChanged() override;
   void OnSensorError() override;
   bool IsNotificationSuspended() override;
 
  private:
   scoped_refptr<PlatformSensor> sensor_;
   mojo::StrongBinding<Sensor> binding_;
   mojom::SensorClientPtr client_;
   bool suspended_;
   DISALLOW_COPY_AND_ASSIGN(SensorImpl);
 };
 
 }  // namespace device
 
 #endif  // DEVICE_GENERIC_SENSOR_SENSOR_IMPL_H_